Eksplorasi dan karakterisasi bakteri aerob ligninolitik serta aplikasinya untuk pengomposan tandan kosong kelapa sawit Exploration and characterization of ligninolytic aerobic bacteria and its application in composting oil palm empty fruit bunch

Abstract

Abstract

Lignin is a complex compounds that makes up the cell walls of plants and is quite difficult to degrade at normal ambient condition.  One of the organic materials with high  lignin content is empty fruit bunches (EFB) of oil palm. So far, the well-studied microorganism to degrade lignin is of a class of fungi. Utilization of bacteria to degrade lignin in EFB has rarely been reported although application of the bacteria is very important if it is associated with aerobic composting which requires regular turning process and supporting clean development mechanism (CDM). The objective of this study was to explore and characterize the bacteria having capability to degrade lignin in EFB. The result showed that from 14 types of sample, 12 and 11 isolates were obtained through non enrichment and enrichment methods respectively. Qualitative test was performed using a lignin derivative dye (methylene blue/MB) suspended in Luria Bertani (LB) solid media and the formation of the clear zone was observed, while quantitative assay was performed with enzyme activity assays of laccase (Lac), manganese peroxidase (Mn-P), and lignin peroxidase (Li-P). The best isolate (FS isolate) was obtained from enrichment method that able to make 0.6 cm clear zone of LB media + MB and actively produced laccase, manganese peroxidase with and without addition of Mn with an activity of 2.68, 20.02, and 0.36 U/mL, respectively. While the best isolate from non enrichment method was CRK 1, that was able to make   0.3 cm clear zone and produced Mn-peroxidase with and without addition of Mn as much as 2.09 and 0.23 U/mL, respectively. Application of the decomposer formula could speed upthe declining rate of C/N ratio and suppressing Escherichia coli and Salmonella sp.in EFB compost produced.

Abstrak

Lignin merupakan senyawa kompleks yang menyusun dinding sel tanaman dan cukup sulit didegradasi secara alami. Salah satu bahan organik yang mempunyai kadar lignin tinggi adalah tandan kosong kelapa sawit (TKKS). Sejauh ini, mikroorganisme yang banyak dipelajari dalam mendegradasi lignin adalah dari golongan jamur. Peng-gunaan bakteri dalam mendegradasi lignin pada TKKS belum banyak dilaporkan walaupun peran bakteri lignino-litik aerob sangat penting jika dikaitkan dengan proses pengomposan secara aerob yang membutuhkan pembalikan secara berkala danprogram clean development mechanism (CDM). Penelitian ini bertujuan mengeksplorasi dan meng-karakterisasi  bakteri  yang  berpotensi  mendegradasi lignin  dalam pengomposan TKKS. Dari 14 jenis sampel diperoleh sebanyak 12 dan 11 isolat melalui metode tanpa dan dengan pengkayaan. Uji kualitatif dilakukan dengan mengukur terbentuknya zona bening pada media Luria Bertani (LB) padat yang mengandung senyawa warna turunan lignin (biru metilen/MB).Uji kuantitatif dilakukan dengan mengukur aktivitaslakase, Mn-peroksidase, dan lignin peroksidase. Hasil penelitian menunjukkan bahwa isolat FS  merupakan isolat terbaik dari metode pengkayaan yang mampu membentuk zona bening pada medium LB + MB  0,6 cm, sedangkan isolat terbaik dari metode tanpa pengkayaan adalah CRK 1 dengan zona bening 0,3 cm pada medium yang sama setelah inkubasisemalam. Isolat FS memiliki aktivitas lakase, Mn-peroksidase dengan dan tanpa Mn berturut-turut adalah sebesar 2,68; 20,02; dan0,36 U/mL, sedangkan isolat CRK 1 memiliki aktivitas Mn-peroksidase dengan dan tanpa Mnberturut-turut adalah 2,09 dan 0,23 U/mL. Aplikasi formula dekomposer pada pengompos-an 200 ton TKKS mampu mempercepat laju penurunan nisbah C/N dan menekan populasi Escherichia coli dan Salmonella sp.